WO2003090997A1

WO2003090997A1 - Manual screen changer

Info

Publication number: WO2003090997A1
Application number: PCT/CH2002/000233
Authority: WO
Inventors: Peter Emhardt
Original assignee: Maag Pump Systems Textron Ag
Priority date: 2002-04-26
Filing date: 2002-04-26
Publication date: 2003-11-06
Also published as: WO2003090999A1; EP1499489B1; AU2002250761A1; EP1499489A1; DE50304477D1; ATE334796T1; AU2003218849A1

Abstract

The invention relates to a device for filtering liquid media such as, in particular, viscous and highly viscous polymer melts. The device comprises at least one screen-like element, which can be repeatedly removed or exchanged while being provided in a plate (1) that is mounted in a manner that enables it to rotate about a center of rotation (A) in order to guide the element into or out of the melt flow. The plate (1) is connected to a drive via a gearing (13', 13'', 15', 15''). The drive preferably consists of a pair of sprockets.

Description

manual screen changers

The present invention relates to a device for filtering liquid media, in particular viscous and highly viscous polymer melts according to the preamble of claim 1, and a method for filtering liquid media, in particular viscous and highly viscous polymer melts.

Melt filters have been used in plastic processing for years to clean contaminated plastic melts. With heavily contaminated melts, more or less automated screen changing devices are used, e.g. Belt screen changer, disc screen changer or also flat slide and pin screen changer. Flat slide valves are described, for example, in US Pat. No. 3,788,484, US Pat. No. 3,962,092, US Pat. No. 4,880,374, EP 114,651, EP 925,904 and DE 19,612,790. In US Pat. No. 2,060,423 a slider with hydraulic drive is disclosed, while in Japanese Disclosure JP 2001 03872 describes a disc screen changer. Some of the devices described are automated and therefore require a drive and control unit.

In many cases, however, it is sufficient to install a simple screen changer in the extrusion line, which is operated manually if necessary. In particular in the case of melts that are not very heavily contaminated, a drive and control unit are dispensed with. Only pressure monitoring is necessary to detect screen contamination.

Such manually operated screen changing devices are usually designed as swivel plate screen changers, as is known, for example, from DE 4 236 348, in which a flat plate with one, two or more screen locations is moved by hand using a lever. The soiled sieve is moved out of the melt flow and can be removed, cleaned and replaced with a new one, while a clean, new sieve enters the melt channel.

Usually, the extrusion system has to be stopped for the changing process or at least the throughput has to be significantly reduced in the case of two screens, so that the pressure from the screen does not increase inadmissibly.

In the case of manual screen changing devices in particular, the screens only have to be changed very rarely, ie once a week or even only once a month. In the meantime, however, the melt often "cakes" between the housing and the sieve plate, so that an increased release torque is necessary to break the plate apart than would be the case with a freshly introduced swivel plate with a new sieve plate. The plant operator therefore uses so that sufficient torque can be applied often an extension (tube) that he pushes over the lever of the hand screen changing device. Usual sizes of such swivel screen changers achieve transmission ratios of the force manually applied by the operator, including the use of an approx. 3 long lever extension through an attached tube of approx to solve. Then a change can only be accomplished with considerable time and manpower by dismantling the screen changing device.

It is characteristic of these solutions of such swivel plate screen changers, which are already known from a wide range of uses, that an increase in the swivel torque can only be achieved by extending the lever length, such as an attached pipe, limited by manageability and available space in the system, or constructively by varying the pivot point. Another characteristic feature of all these known solutions is that the pivoting range of the lever is always the same as the pivoting range of the pivoting plate, i.e. the movement is not increased or decreased.

Accordingly, it is the object of the present invention to propose a swivel plate screen changer which is easier to handle, takes up less space and nevertheless enables perfect operation. According to the invention, the object is achieved by means of a device according to the wording of claim 1. It is proposed that the device for filtering viscous and highly viscous media, such as, in particular, polymer melts, has at least one removable or replaceable, sieve-like organ, which is arranged in a pivotable plate mounted about a fulcrum around the organ in or out of the Lead melt flow, the plate is connected to a drive via a gear.

Preferred embodiments of the device according to the invention are characterized in the dependent claims.

The present invention provides a simple, inexpensive screen changing device which solves the above-mentioned problems, in which a simple, inexpensive power transmission from i = 20 to i = 50-100 by means of a simple gear, for example consisting of two gear wheels, is realized.

The invention will be explained in more detail with reference to the attached figures and described below. Show:

La and lb schematically an embodiment of a device according to the invention in plan view from the front and in section, 2 shows the transmission-type drive from FIG.

3a to 3e schematically illustrate the actuation of the device according to the invention, FIGS. 4a and 4b a further practical embodiment variant of the device according to the invention in plan view and in section,

5a and 5b a further embodiment variant of the device according to the invention in plan view in two different operating positions, and

6, analogously to FIG. 5, in turn, a further embodiment variant of the device according to the invention.

A swivel plate screen changer according to the invention is shown in FIGS. 1 a and 1 b, FIG. 1 a schematically showing the screen changer in a front plan view, while in FIG. 1 b the same changer is shown in section.

The swivel plate screen changer has a central swivel plate 1, which is pivotably mounted about an axis A between the two housing plates 3 and 5. In the swivel plate 1, two bores or screen receiving cavities 9 and 11 are arranged, provided for the use of melt filters or filter screens in order to filter viscous or highly viscous media, in particular polymer melt. A through hole 7 is provided in each of the two housing plates 3 and 5 for driving the liquid polymer melt through. In the illustration according to FIG. 1 a, the passage through the bore 7 would be closed by neither of the two cavities 9 or 11 being arranged with the filter screens in the area of the through bore 7.

In order now to pivot the swivel plate 1 relative to the two housing plates 3 and 5 about the axis of rotation A, the toothed wheels 15 'or 15 "mounted in the swivel plate 1 are to be rotated about the axis B or about the shaft 17 by means of a crank 19, which gearwheels 15 'and 15 "are in engagement with a gearwheel 13' and 13", respectively. The latter two gearwheels 13 'and 13 "are each firmly connected to one of the housing plates 3 and 5, respectively.

In Fig. 2, the drive or the gears from Fig. La is shown in an enlarged view. It can now be clearly seen that when the crank 19 is actuated about the shaft 17 or axis of rotation B, the two gearwheels 15 ′ or 15 ″ which are arranged laterally from the swivel plate 1 in one or the other direction of the arrow along the two gearwheels 13 ′ or 13 "can be moved. As a result, however, the swivel plate 1 is also moved about the axis of rotation A in order to move one of the two cavities 9 or 11, containing the filter screens, into the region of the through bore 7. This process can be understood schematically with reference to FIGS. 3a to 3e. In Fig. 3a, the pivot plate 1 is shown in the starting position corresponding to Fig. La. By turning the lever 19 by the angle α, the swivel plate 1 is moved to the right by the angle β. By further moving the lever 19, the pivoting plate 1 is pivoted further until finally the cavity 9, containing the filter screen, comes to rest completely in the area of the through bore 7 of the two housing plates 3 and 5. It is now possible to flow through and filter the polymer melt.

The use of a significantly enlarged translation of the manual force of the plant operator proposed according to the invention ensures that a significantly increased torque is available for the movement of the swivel plate without the size of the screen changing device changing significantly.

In the case of the invention, particular care was taken to ensure that it is a simple, technically known to any mechanic and thus easy to use and easy to maintain or replace in the event of damage, consisting of two gears.

Manually operated screen changer models, consisting of a housing, have two housing plates arranged in parallel, in the middle of which a movable plate how the pivot plate is arranged rotatably mounted about a pivot point is known by industrial use. What is new is that the swivel plate, in which the bores or screen receiving cavities are located, in which a support plate such as perforated plate and the screen fabric placed thereon is introduced, is moved around the pivot point A by means of the gear proposed according to the invention, so that the cavities can be moved into or out of the melt channel. What is new is that at least one gearwheel is fixed on the housing plates in a rotationally fixed manner, on which at least one gearwheel of smaller diameter rotatably mounted in or on the swivel plate rolls. As a result of this rolling, the swivel plate is swiveled around the pivot point A together with the smaller driving gear.

Depending on the selected ratio, it is not necessary to attach the large gear as a separate part to the housing; this is only recommended for relatively large gear ratios, in which the small gear wheel may travel more than one revolution and may be driven by a crank. For such a crank, the axis of the small gear is extended so that the crank can be freely rotated outside the screen changing device. As an alternative to the crank, a so-called ratchet can of course also be used.

With the large gear, it could be sufficient to attach the toothing or only a part of it directly to the housing plates. Particularly with high breakaway torques to be expected, a symmetrical arrangement of the teeth on the left and right of the swivel plate is recommended for an even application of force and reduction of the forces occurring in the teeth.

The selected gear ratio between small gear (movable) and large gear (fixed to the housing) ensures that the torque required to move the swivel plate is increased according to the gear ratio (ratio of the number of teeth).

With a selected ratio of 1: 5, this means, for example with reference to FIG. 3, that in order to move the swivel plate through the angle β, for example 5 °, the lever must be rotated through the angle α, such as 25 °.

With the screen changing devices it should be noted that the breakaway torque in particular can be very high. Once this breakaway torque is exceeded and the swivel plate has already moved a bit, a significantly smaller torque is usually required to swivel the swivel plate.

To support the force application at the time of

Breakaway, additional threaded elements (which otherwise serve as stops) can be used to create another To allow force introduction. The use of a striking pin (actuation by means of a hammer) for better overcoming the breakaway torque is also conceivable.

Another major advantage of the manually operated screen changer with power amplification is that no hydraulic cylinders are necessary, so that it can also be used in areas with special "food regulations" such as the food industry is possible.

4a and 4b show a further practical embodiment variant of a device according to the invention.

One is arranged between two housing plates 23 and 25

Swivel plate 21, having the two bores or screen receiving cavities 29 and 31, in each of which a support plate and the screen fabric placed thereon are introduced. In the illustration according to FIG. 4a, the swivel plate is arranged in such a way that the screen receiving cavities 31 with filter screen 30 and the through bores 22 and. 24 are arranged in line in the housing plates 23 and 25 for the passage of the polymer melt. The two housing plates 23 and 25 are positioned by means of bolts / nuts 32 and held together.

The pivot plate 21 is rotatably mounted about the bolt or the axis A, the rotary movement by means of a Gear 37 takes place, which can be moved about an axis B on the gear contour 33 fixedly connected to the housing plate 25. It is driven by a crank 39.

If, in operation, an excessively high pressure is measured in the inflowing polymer melt in the through hole 22, which indicates that the filter screen 30 in the screen receiving cavity 31 is too heavily contaminated, the gearwheel 37 is moved by means of the crank 39 along the housing plate 25 arranged gear 33 moves. As a result, the screen receiving cavity 31 is moved away, and the screen receiving cavity 29 thus passes between the through bores 22 and 24. As a result of the still unpolluted filter screen in the screen receiving cavity 29, the polymer melt can pass through the screening device into the through bore 24 relatively unhindered. On the other hand, the filter screen 30 in the screen receiving cavity 31 in the recess 44 of the two housing plates 23 and 25 can then be cleaned.

5 and 6, the practical device of FIGS. 4a and 4b is shown, but containing stops in order to limit the movement of the gearwheel 37 along the gearwheel 33 such that only a pivoting movement of the pivoting plate 21 between the two desired positions Sieve receiving cavity 29 in line with the through bores 22 and 24 and sieve receiving cavity 31 in line with the through bores 22 and 24 - can take place. 5a and 5b, which shows the top view of the device in the two extreme positions, an eccentric and a stop 41 or 43 are provided which limit the movement of the gearwheel 37 itself.

6a and 6b, instead of the eccentric with a stop, for example a hole breaking thread and stop 47 or 49 are provided. In the case of piercing thread and stop in particular, there is the great advantage that the additional force necessary to break loose can be achieved by actuating one or the other piercing thread. It is also possible to provide a striking pin instead of a thread centrally in the stop, which can be actuated by means of a hammer in the direction of the swivel plate.

The representations in FIGS. 1 to 6 are of course only examples which can be changed, supplemented or modified in any desired manner. So it is of course possible to provide only one housing plate. Instead of each of the two gear transmissions in Fig. 1, only a single gear transmission can be used. Instead of the two screen receiving cavities shown in each case, only one or three or more such screen receiving cavities can be provided, etc.

Finally, a worm gear can also be used instead of a gear transmission. The transmission ratio can of course be chosen as desired; it is important that the necessary force for the drive is can be witnessed so that in particular a breakaway of the swivel plate when changing the filter screens or the necessary breakaway torque can be achieved.

Claims

Expectations :

1. Device for filtering liquid media, in particular viscous and highly viscous polymer melts, comprising at least one removable or replaceable, sieve-like organ, arranged in a pivotable plate (1, 21) mounted about a pivot point (A), around the organ in or to lead from the melt stream, characterized in that the plate (1, 21) is connected to a drive via a gear (13 ', 13 ", 15', 15"; 33, 37).

2. Device according to claim 1, characterized in that the swivel plate is preferably arranged pivotably perpendicular to the melt flow.

3. Device, in particular according to one of claims 1 or 2, characterized in that the pivot plate (1, 21) between two housing plates (3, 5, 23, 25) is pivotally arranged.

4. Screen changing device according to one of claims 1 to 3, characterized in that the transmission consists of at least one gear pair.

5. Screen changing device according to one of claims 1 to 4, characterized in that the transmission has a transmission ratio.

6. Screen changing device according to one of claims 3 to

5, characterized in that the one gear wheel (13 ', 13 ", 33) is fixedly, in particular rotatably, connected to at least one of the screen changer housing plates.

7. Screen changing device according to one of claims 1 to

6, characterized in that the axis of the one gearwheel coincides with the axis of rotation (A) of the swivel plate (1, 21).

8. Screen changing device according to one of claims 3 to

7, characterized in that the one gear (13 ', 13 ", 33) on which the drive engages is part of at least one of the screen changer housing plates.

9. Screen changing device according to one of claims 1 to

8, characterized in that the axis (B) of the other gear (15 ', 15 ", 37) is mounted in the swivel plate (1, 21).

10. Screen changing device according to one of claims 1 to

9, characterized in that the axis (B) of the other gear describes a rotational movement about the pivot point (A) of the one gear.

11. Screen changing device according to one of claims 1 to

10, characterized in that the other gear is arranged rolling on the one gear.

12. Screen changing device according to one of claims 1 to 11, characterized in that mechanical drive means such as a lever, a ratchet or a crank are provided for moving the other gear (15 ', 15 ", 37) along the one gear (13' , 13 ", 33) for moving the swivel plate (1, 21) around the pivot point (A).

13. Screen changing device according to one of claims 1 to 11, characterized in that hydraulic or electrically driven motor means are provided for

Moving the other gear (15 ', 15 ", 37) along the one gear (13', 13", 33) to move the pivot plate (21) around the pivot point (A).

14. Screen changing device according to one of claims 1 to 13, characterized in that the swivel plate has at least one, preferably two or more screen receiving cavities (9, 11, 29, 31).

15. Screen changing device according to one of claims 1 to 14, characterized in that stop means (41, 43, 45, 47) are provided for limiting the movement of the pivot plate (1, 21).

16. Screen changing device according to one of claims 1 to 15, characterized in that the other gear is a worm shaft, which by helical rotary movement along the one gear for the rotary movement of the swivel plate is moved.

17. Screen changing device according to one of claims 1 to 16, characterized in that means for increasing the breakaway torque are provided, such as in particular gear means such as e.g. a worm gear; Means for generating an additional moment, optionally arranged in stop means for limiting the movement of the swivel plate, etc.

18. Process for replacing and / or removing at least one sieve-like organ for filtering viscous and highly viscous media, such as in particular polymer melts, arranged in a pivotable plate mounted about a pivot point in order to guide the organ into or out of the melt stream characterized in that the swivel plate is moved by means of a gear such as in particular a gear transmission.

19. The method according to claim 18, by means of a device according to one of claims 1 to 17, characterized in that the pivoting plate is moved in relation to at least one housing plate by moving the other gear of the transmission around the one gear.

20. Use of the device according to one of claims 1 to 17 for replacing and / or removing a sieve-like organ for filtering viscous and highly viscous media such as, in particular, polymer melts, arranged in a pivotable plate mounted around a pivot point to guide the organ into or out of the melt stream.